With increased longevity of diabetics resulting from insulin and antibiotic therapy, the chronic sequelae of diabetes have become more important in the management of these patients. Macrovascular dysfunction and impairment of cell-mediated immune response are two clinically important complications of diabetes. This proposal attempts to clarify the regulatory role of hormones in the genesis and course of these sequelae at the cellular level. Endothelial cells (EC's) lining the vascular system respond to pathological states in two major and intimately related ways: locomotion and proliferation. We plan to study the locomotor and mitogenic responses of cultured aortic EC monolayers to linear wounding and changes in the hormonal milieu. Specifically, we shall use immunofluorescence microscopy, time-lapse cinemicrophotography, 3H-thymidine nuclear labeling-autoradiography, and needle miroinjection to observe the following EC responses: 1) the rapid cytoplasmic movement and orientation of centrosomes prior to and during EC movement into the wound path, and 2) changes in the state of the cytoskeletal frame of EC's bordering the wound in relation to their locomotor and mitogenic responses. We shall determine: 1) what specific hormones that attain abnormal circulating levels in diabetes control the centrosomal orientation response to wounding, 2) the mechanism of such regulation, 3) the regulatory role of arachidonic acid metabolites in this centrosomal response, 4) the effect of increased glycosylation on EC movement and proliferation, and 5) whether needle-microinjecting EC's with antibodies against the centrosome and cytoskeletal proteins can modulate cellular response. Diabetic patients also exhibit an inadequate proliferative response of their T-lymphocytes to various antigenic stimuli. This impairment improves with better metabolic control implying that the hormonal milieu is regulating cell-mediated immunity. Somatostatin (SS) attains high blood concentrations in diabetes which decrease with improved metabolic control, is localized in the thymus gland, and blunts concanavalin A-induced rat thymocyte DNA synthesis. We shall investigate the possibility that SS is one of the thymic humoral factors that impair cell-mediated immunity in diabetes by studying in streptozotocin- and BB-diabetic rats the following: 1) localization of SS secreting cells in the thymus of normal, diabetic and treated rats by freeze-fixation and immunofluorescence, 2) changes in thymic SS concentration by radioimmunoassay, and 3) the isolation and culture of the SS-secreting thymic cells.